The osmotic pressure of a solution can be calculated using the formula:

Osmotic Pressure (π) = MRT

Where:
- M is the molarity of the solution
- R is the ideal gas constant (0.0821 L·atm/mol·K)
- T is the temperature in Kelvin

In this case, we are given two solutions and need to find the osmotic pressure of the mixture.

Step 1: Convert the given percentages to molarities.

The molarity (M) of a solution can be calculated using the formula:

Molarity (M) = (mass of solute in grams / molar mass of solute) / volume of solution in liters

For the urea solution:
- Mass of urea = 1.5% of 100 mL = 1.5 g
- Molar mass of urea (m) = 60 g/mol
- Volume of solution = 100 mL = 0.1 L

Molarity of urea solution (M1) = (1.5 g / 60 g/mol) / 0.1 L = 0.25 M

For the cane sugar solution:
- Mass of cane sugar = 3.42% of 100 mL = 3.42 g
- Molar mass of cane sugar (m) = 342 g/mol
- Volume of solution = 100 mL = 0.1 L

Molarity of cane sugar solution (M2) = (3.42 g / 342 g/mol) / 0.1 L = 0.1 M

Step 2: Calculate the total molarity of the mixture.

Since the volumes of both solutions are equal, the total molarity of the mixture (M) is the average of the molarities of the two solutions.

M = (M1 + M2) / 2 = (0.25 M + 0.1 M) / 2 = 0.175 M

Step 3: Convert the temperature to Kelvin.

The given temperature is 20 °C, which is equivalent to 20 + 273.15 = 293.15 K.

Step 4: Calculate the osmotic pressure.

Using the formula π = MRT, we can substitute the values:

π = (0.175 M) * (0.0821 L·atm/mol·K) * (293.15 K)

π = 4.07 atm

Therefore, the osmotic pressure of the mixture of the two solutions is 4.07 atm.